A structure of a methanol reforming hydrogen high-temperature fuel cell stack

Abstract

The application discloses a structure of a methanol reforming hydrogen high-temperature fuel cell stack. The technical scheme of the application is: comprising a first end plate, a second end plate, a bipolar plate assembly arranged between the first end plate and the second end plate, and a screw rod assembly for fixing the first end plate, the second end plate and the bipolar plate assembly, the upper and lower parts of the bipolar plate assembly are respectively provided with a current equalizing cover plate and a bottom plate connected with the first end plate and the second end plate, the bipolar plate assembly comprises heat insulation plates arranged on both sides and a current collecting plate, the current collecting plate is provided with hydrogen and oxygen inlets and outlets, the bipolar plate assembly comprises a plurality of reaction units connected in sequence, each reaction unit comprises two bipolar plates and a membrane electrode, a proton exchange membrane and a large sealing ring arranged between the two bipolar plates, small sealing rings are arranged between the reaction units, and the bipolar plates are provided with cooling flow channels. The scheme provided by the application has the advantages of large stack cooling temperature difference, large power generation, long service life and convenient disassembly and assembly.

Description

Technical Field

[0001] This invention relates to the field of high-temperature fuel cell technology, and in particular to the structure of a high-temperature fuel cell stack for methanol reforming to produce hydrogen. Background Technology

[0002] High-temperature fuel cells (HTFCs) are a new type of power generation device that directly converts the chemical energy of fuel (such as hydrogen) and oxidant (such as oxygen) into electrical energy. Because the energy conversion is not limited by the Carnot cycle and the only byproduct is water, and because the water is in a high-temperature environment, it is discharged as steam through the bipolar plate channels. Therefore, HTFCs have high energy conversion efficiency and are environmentally friendly. Hydrogen is the best fuel for fuel cells, and large companies in developed countries related to automobiles and energy are accelerating the development of fuel cells. Currently, there are still many technical challenges in hydrogen storage, transportation, distribution, and refueling, thus failing to meet the supply demands of fuel cells of various sizes. Hydrogen-rich fuels such as alcohols and hydrocarbons can be used to provide hydrogen sources for fuel cells through reforming, either mobilely or on-site. This method has advantages such as high energy density, high energy conversion rate, ease of transportation and portability, and economic and safety benefits. Methanol-water reforming is one of the most widely accepted and effective reforming methods for hydrogen production in the market. High-temperature fuel cells for methanol reforming to produce hydrogen have the following advantages: 1. High safety performance, as methanol can be directly reformed to produce hydrogen without involving hydrogen storage issues; 2. Simple bipolar plate structure, with product water discharged as water vapor under high-temperature conditions, and no drainage channels in the bipolar plates; 3. Small stack temperature difference and high efficiency, with a uniform flow structure for the cooling shroud and separation of cooling and cathode channels; 4. Low hydrogen purity requirements, as the hydrogen content requirement is low under high-temperature conditions; 5. No NOx or SOx in the exhaust gas, and the products of the reforming hydrogen production reaction are free of NOx and SOx. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the main objective of this invention is to provide a structure for a methanol reforming hydrogen production high-temperature fuel cell stack with a large stack cooling temperature difference, large power generation capacity, long lifespan, and convenient assembly and disassembly.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a structure for a methanol reforming hydrogen production high-temperature fuel cell stack, comprising a first end plate, a second end plate, a bipolar plate assembly disposed between the first and second end plates, and a screw assembly for fixing the first end plate, the second end plate, and the bipolar plate assembly. A flow equalization cover plate and a bottom plate, connected to the first and second end plates, are respectively disposed above and below the bipolar plate assembly. The bipolar plate assembly includes heat insulation plates and current collectors disposed on both sides. Hydrogen and oxygen inlets and outlets are provided on the current collectors. The bipolar plate assembly includes several reaction units connected in sequence. Each reaction unit includes two bipolar plates and a membrane electrode assembly, a proton exchange membrane, and a large sealing ring disposed between the two bipolar plates. Small sealing rings are disposed between the reaction units. Cooling channels are provided on the bipolar plates.

[0005] Preferably, both the first end plate and the second end plate are provided with connecting blocks that can be connected to the flow equalization cover plate and the bottom plate. The upper part of the connecting block of the first end plate is provided with an air inlet hole communicating with the flow equalization cover plate, and the lower part of the connecting block of the second end plate is provided with an air outlet hole communicating with the bottom plate. The flow equalization cover plate is provided with a flow equalization plate, and the flow equalization plate is provided with multiple through holes.

[0006] Preferably, the large sealing ring includes a bi-peak sealing ring that fits tightly against the bipolar plate.

[0007] Preferably, the cooling channel is a serpentine channel.

[0008] Preferably, the through hole includes a small through hole near the first end plate and a large through hole near the second end plate.

[0009] Preferably, the screw assembly includes a screw, a nut, and a spring.

[0010] This invention offers the following advantages over existing technologies, solving problems such as large cooling temperature differences, low power generation, short lifespan, and difficult assembly / disassembly in current fuel cell stacks. The stack is sealed by a screw assembly that locks the stack in place, and large and small sealing rings seal each contact surface to prevent gas leakage. (See reference...) Figure 4 The reformed hydrogen gas enters the bipolar plate hydrogen flow channel axially through an inlet on one side of the collector plate, and flows through a serpentine flow channel to exit at the diagonally opposite outlet; (Refer to...) Figure 5Air enters the bipolar plate axially through an inlet on one side of the collector plate at the other end, flowing through a serpentine channel to exit at a diagonally opposite outlet. Within the bipolar plate's channels, hydrogen gas passes through the gas diffusion layer on the membrane electrode to reach the catalyst-coated proton exchange membrane. Hydrogen protons pass through the proton exchange membrane and enter the oxygen side, while electrons reach the oxygen side via the external circuit. Hydrogen protons, electrons, and oxygen molecules react with the catalyst to form water, which is then discharged. Cooling air enters through the air inlets of the flow equalization cover and connecting block. The flow equalization plate ensures the cooling gas flows evenly through the cooling channels of the bipolar plate, and the gas reaches the bottom plate and exits through the air outlet. The flow equalization cover and bottom plate are bolted to the two end plates for easy disassembly and replacement. The separate structure of the cooling air channel and cathode inlet air channel reduces the thickness of the bipolar plate, decreases the overall volume, and lowers manufacturing costs. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of a high-temperature fuel cell stack for methanol reforming to produce hydrogen according to the present invention.

[0012] Figure 2 This is a partially exploded view of the structure of a high-temperature fuel cell stack for methanol reforming to produce hydrogen according to the present invention.

[0013] Figure 3 This is a schematic diagram of a bipolar plate.

[0014] Figure 4 This is a diagram showing the flow path of hydrogen.

[0015] Figure 5 This is a diagram showing the flow path of oxygen.

[0016] Figure 6 This is a diagram showing the airflow path.

[0017] Figure 7 This is a schematic diagram of the flow equalization cover plate.

[0018] In the diagram: 1. First end plate; 2. Second end plate; 3. Screw assembly; 4. Bipolar plate assembly; 5. Flow equalization cover plate; 6. Base plate; 7. Heat insulation plate; 8. Collector plate; 9. Hydrogen and oxygen inlet and outlet; 10. Bipolar plate; 11. Membrane electrode; 12. Proton exchange membrane; 13. Large sealing ring; 14. Small sealing ring; 15. Cooling channel; 16. Connecting block; 17. Air inlet; 18. Air outlet; 19. Flow equalization plate; 20. Through hole. Detailed Implementation

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] like Figure 1As shown, a structure of a methanol reforming hydrogen production high-temperature fuel cell stack includes a first end plate 1, a second end plate 2, a bipolar plate assembly 4 disposed between the first end plate 1 and the second end plate 2, and a screw assembly 3 that fixes the first end plate 1, the second end plate 2, and the bipolar plate assembly 4. A flow equalization cover plate 5 and a bottom plate 6, connected to the first end plate 1 and the second end plate 2, are respectively disposed above and below the bipolar plate assembly 4. The bipolar plate assembly 4 includes heat insulation plates 7 and current collector plates 8 disposed on both sides. Hydrogen and oxygen inlets and outlets 9 are disposed on the current collector plates 8. The bipolar plate assembly 4 includes several reaction units connected in sequence. Each reaction unit includes two bipolar plates 10 and a membrane electrode assembly 11, a proton exchange membrane 12, and a large sealing ring 13 disposed between the two bipolar plates 10. Small sealing rings 14 are disposed between the reaction units. Cooling channels 15 are disposed on the bipolar plates 10.

[0021] Preferably, both the first end plate 1 and the second end plate 2 are provided with connecting blocks 16 that can be connected to the flow equalization cover plate 5 and the bottom plate 6. The upper part of the connecting block 16 of the first end plate 1 is provided with an air inlet hole 17 communicating with the flow equalization cover plate 5, and the lower part of the connecting block 16 of the second end plate 2 is provided with an air outlet hole 18 communicating with the bottom plate 6. The flow equalization cover plate 5 is provided with a flow equalization plate 19, and the flow equalization plate 19 is provided with a plurality of through holes 20.

[0022] Preferably, the large sealing ring 13 includes a double-peak sealing ring that fits tightly against the bipolar plate 10. The large sealing ring 13 adopts a double-peak sealing structure in cross-section to ensure that gas does not leak in the event of single-peak seal failure.

[0023] Preferably, the cooling channel 15 is a serpentine channel.

[0024] Preferably, the through-hole 20 includes a small through-hole 20 near the first end plate 1 and a large through-hole 20 near the second end plate 2. The use of through-holes 20 of varying sizes in the flow-equalizing cover plate 5 minimizes the temperature difference between the bipolar plates 10 of the fuel cell stack, improving the stack's efficiency and lifespan. This design is based on the fact that the airflow is greater near the first end plate 1, hence the smaller through-hole 20 is used there. The through-holes 20 at subsequent points are larger because the airflow decreases, ensuring that the airflow to each part of the bipolar plate assembly 4 is roughly the same or that the temperature difference is small.

[0025] Preferably, the screw assembly 3 includes a screw, a nut, and a spring.

[0026] This solution presents a structure for a high-temperature fuel cell stack used in methanol reforming for hydrogen production. This structure addresses issues such as large cooling temperature differences, low power generation, short lifespan, and difficult assembly / disassembly in existing fuel cell stacks. The stack is sealed by a screw assembly 3, which locks the stack in place. Large and small sealing rings 13 and 14 seal each contact surface to prevent gas leakage. (Refer to...) Figure 4The reformed hydrogen gas enters the hydrogen flow channel of the bipolar plate 10 axially through the inlet on one side of the collector plate 8, and flows through the serpentine flow channel to the diagonally opposite outlet; (Refer to...) Figure 5 Air enters the bipolar plate 10 axially through the inlet on one side of the collector plate 8 at the other end, and flows through a serpentine channel to exit at the diagonally opposite outlet. Hydrogen gas within the bipolar plate 10 passes through the gas diffusion layer on the membrane electrode 11 to the proton exchange membrane 12 coated with the catalyst. Hydrogen protons pass through the proton exchange membrane 12 and enter the oxygen side, while electrons reach the oxygen side through the external circuit. Hydrogen protons, electrons, and oxygen molecules react with the catalyst to form water, which is then discharged. Cooling air enters through the air inlet 17 of the flow equalization cover plate 5 and the connecting block 16. The flow equalization plate 19 ensures the cooling gas flows evenly through the cooling channels 15 of the bipolar plate 10, and the gas reaches the bottom plate 6 and exits through the air outlet 18. The flow equalization cover plate 5 and the bottom plate 6 are bolted to the two end plates, allowing for easy disassembly and replacement. The separate structure of the cooling air channel and the cathode inlet air channel reduces the thickness of the bipolar plate 10, decreases the overall volume, and lowers manufacturing costs.

[0027] It should be noted that this solution is applicable to the static power generation of methanol reforming hydrogen fuel cells. However, due to external environmental factors such as severe vibration and impact, which may cause internal displacement and leakage of the fuel cell stack, it is not suitable for high-vibration vehicle-mounted applications. Prolonged severe vibration can cause internal displacement and leakage of the fuel cell stack, thereby reducing its power generation capacity and shortening its lifespan. Nevertheless, this solution has significant market potential in static power generation, such as in portable generator sets, fixed power stations in remote mountainous areas, and isolated power stations, where it offers considerable advantages.

[0028] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A structure of a hydrogen reforming methanol high temperature fuel cell stack, characterized by: The application relates to a fuel cell, which comprises a first end plate, a second end plate, a bipolar plate assembly arranged between the first end plate and the second end plate, and a screw rod assembly for fixing the first end plate, the second end plate and the bipolar plate assembly, wherein the bipolar plate assembly is provided with a current equalizing cover plate and a bottom plate which are connected with the first end plate and the second end plate respectively, the bipolar plate assembly comprises heat insulation plates arranged on both sides and a current collecting plate, the current collecting plate is provided with hydrogen and oxygen inlets and outlets, the bipolar plate assembly comprises a plurality of reaction units which are connected in sequence, each reaction unit comprises two bipolar plates and a membrane electrode, a proton exchange membrane and a large sealing ring which are arranged between the two bipolar plates, small sealing rings are arranged between the reaction units, cooling flow channels are arranged on the bipolar plates, the first end plate and the second end plate are both provided with connecting blocks which can be connected with the current equalizing cover plate and the bottom plate, the upper part of the connecting block of the first end plate is provided with an air inlet hole which is communicated with the current equalizing cover plate, the lower part of the connecting block of the second end plate is provided with an air outlet hole which is communicated with the bottom plate, the current equalizing cover plate is provided with a current equalizing plate, the current equalizing plate is provided with a plurality of through holes, and the large sealing ring comprises a bimodal sealing ring which is tightly combined with the bipolar plate.

2. The structure of a methanol reforming hydrogen high temperature fuel cell stack according to claim 1, characterized in that: The through holes comprise small through holes close to the first end plate and large through holes close to the second end plate.

3. The structure of a methanol reforming hydrogen high temperature fuel cell stack according to claim 1, wherein: The screw rod assembly comprises a screw rod, a nut and a spring.

Images